Compartmented inflatable articles and the like and method for making the same



Nov. 22, 1955 J. G. PUGH 2,724,129

COMPARTMENTED INFLATABLE ARTICLES AND THE LIKE AND METHOD FOR MAKING THE SAME Filed March 6, 1955 IN VEN TOR. JH/V G PUGH A7' TURA/EY United States Patent iice COMPARTMENTED INFLATABLE ARTICLES AND THE LIKE AND METHOD FOR MAKING THE SAME l `lohn G. Pugh, Lafayette, Calif. i n Application March `6, 1953, Serial No. 340,719 8 Claims. (Cl. 5--349) the compartments have been made by fusing linear portions of the sheets together. These plastic air cushions have proven very satisfactory, are lighter in weight than `cushions made from rubberized cloth, and are less expensive to manufacture. Difficulties have arisen, however, in connection with the` `air passages that join adjacent compartments and that transfer air between them when the mattress is being inflated or deilated and when the user `shifts his position on an inated mattress. The weak spot in such a mattressis at the end of the fused seam adjacent each air transfer passage. The pull applied on the end of the `fused seam tearsthe plastic `sheets so they leak. Thousands of air mattresses have been returned to the manufacturers because of leakage resulting from this problem. 4Even when great care was taken by the manufacturer and mattresses were tested out beforehand and were checked out as satisfactory, still the stresses on the end of the `seams in the area of the transfer passages continued to cause ruptures that ruined the entire mattress.

The present invention has solved this problem by providing a novel type of air passage between` sections. As a result, uniformly satisfactory air mattresses can now be produced from very thin lightweight plastic sheet materials. I take advantage of the fact that the side pull on a bonded seam will `resist tearing, whereas the end pull on such a seam will tear.

The structure which has solved the problem includes, inaddition to the pair of plastic sheets and the fused compartment wall with an opening therethrough, a semirigid plastic tube placed crosswise in the opening and preferably an additional lightweight plastic tube interposed between and secured to said semi-rigid tube and said plastic sheets. The invention also includes a novel method for manufacturing the product of this invention.

Other objects and advantages of the invention will appear from the following detailed description presented in accordance with U. S. Revised Statutes, Section 4888. It is not intended that the` description of details of structure should limit the invention, because it is obvious that changes may be made in` details without departing from the scope of the invention as defined in the claims.

In the drawings: n

Fig. 1 is a reduced plan view of ,an air `mattress embodying the principles of the present invention.

Fig. 2 is an enlarged fragmentary plan'view of the Patented Nov. 22, 1955" mattress of Fig. 1 taken in the region of one of the air transfer passages.

Fig. 3 is a view in perspective of a portion of the device shown in Fig. 2 with part of the sheets cut away to show the air transfer device.

Fig. 4 is a cross-sectional view taken along the line 4-4 of Fig. 2 and showing the first step of the method of making the present invention.

` Fig. 5 is a view similar to Fig. 4 showing the next step in which the thin plastic interposed member is secured into position.

Fig. 6 is a view similar to Figs. 4 and 5 showing the completed air transfer passage.

The invention is applicable to any article where air transfer is involved between two compartments, and especially where the article is made from a single, folded sheet or from two facing sheets of a thermoplastic material. To illustrate the principles of the invention, it will be explained in connection with the air mattress 10 shown in Fig. 1.

The mattress 10 is made up of two plastic sheets 11 and 12 (see Figs. 3 through 6) or from one large plastic sheet folded on the edge 13 so that, in effect, it becomes two overlying sheets. When the partitions are completed, the sheets 11 and 12 may be sealed around the edges by fusing them together to form seams 14, 15, 16, and 17. The valve 18, usually located in one corner, is used to inflate and deflate the mattress 10.

The mattress 1t) is divided into a series of compartments 21, 22, 23, 24, 25, and 26 by fusing together linear portions of the two sheets 11, 12 to form a series of parallel inner compartment longitudinal seams 31, 32, 33, 34, and 35, that run between the end seams 15 and 17. Near the end seams 15 and 17 each longitudinal seam 31, 32, 33, 34, and 35 is crossed by an air transfer passage 40. These air transfer passages 40 allow air flow from one compartment to another so that the entire mattress 10 can be iniiated by forcing air in through the single valve 18. They also act to equalize the air pressure in all the compartments when unequal compression of the compartments occurs in use of the mattress.

It is at these air transfer passages 4tl that the main problem occurs. The load raises the air pressure which tends to pull the two sheets 11 and 12 apart along the longitudinal seams. The weakest point on these is at the end of the seam Where the bonding is omitted to provide the air passage. The tear starts where the bond starts. The present invention solves the problem by providing a continuous bond of the sheets 11 and 12 along the longitudinal seams from end to end. The air passage is in the unbonded walls of an inset. Its structure may best be understood by considering at this point the preferred method of manufacture.

Referring first to Fig. 4, the two sheets 11 and 12 are shown ready to be fused to form a longitudinal seam 31 having eventual provision for an air passage 40 between compartments 21 and 22. Where the air passage is desired, a thin flattened tube 43 of plastic is interposed between the two sheets 11 and 12. The tube 43 may be formed either by extrusion or by folding a single strip of plastic and seaming it at 44. In either event, it is thin, having a wall thickness preferably of about 0.012 inch. One end is made by the fold 45a and the other end 45b by the seam which can be a very strong bond. This seam 44 will be as strong as the mattress side seams 14, 15, 16 and 17 and will resist separation. This tube will take the strain when the mattress is in use instead of throwing that strain onto the end of each seam 31, 32, 33, 34 and 35 adjacent the openings 40. To prevent the tube walls from bonding together and becoming Ysimply a double layer of plastic with no air passage at all, a thin separating strip 45 is inserted inside the tube 43.- A11 example of material suitable for the strip 45 is siliconecoated glass liber cloth about 0.004 inch thick. It will not bond to the walls of tube 43' and is later removed.

The prepared sheets 11 and 12 are now ready to be run through a seaming machine (not shown)` where they are pressed together and subjected to a temperature which causes them to fuse. The seam 31 actually carries right over the portion of the material Where the air passage 40 is to be, so that there is no interruption of the seam and the hollow tube 43 is bonded to the sheets 11 and 12.

The operator has not yet closed the mattress edge and end seams 14, 15, 16 and'17, so he has easy access to the longitudinal seams inthe area where the air passages are to be.

Next-each separator strip 45 is removed from each tube 43 and a substantially round semi-rigidshort plastic tube section 46 is forced inside the thin plastic tube 43. The tube 46 may be made of a vinyl plastic or some similar material, and preferably it is cemented or otherwise bonded to the tube or envelope 43, thereby completing the air transfer device. The tubes 43 plus the continuous longitudinal seams in the sheets 11 and 12 provide the strength needed, but I prefer a construction employing the tubes 46 because they will hold open the ends of the tube 43. If not held open by some spacer means, the ends of the tube 43 tend to act like a valve sealing against the passage of air. As shown in Figs. 3 and 6, the tube or envelope 43 is llarger than the tube 46, so that the tubes 43, 46 are preferably cemented together only along a portion 52, 53 of their upper and lower surfaces to hold the tube 46 in place.

As shown in Fig. 6, when the air pressure rises in the mattress compartments, the expansive force at 51 will be resisted by the continuous wail 45a thereby protecting the seam between the sheets 11 and 12. Also at 45b the same protections will vbe provided by the tube seam 44.

What my invention has done is to leave no place in the bonded mattress seams where an end of a seam is exposed to a separative force but instead the strain is all taken on the edges of seams.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not `intended to be in any sense limiting.

I claim:

l. The improvement in the construction of inflatable objects made ofsheet material having at least two comf partments, with each compartment separated from its adjacent compartment by a seam made by bonding said sheets to each other, which consists in having in each 'seam air passage means comprising a tube-like member extending generally crosswise to said seam between said sheets, and bonded on its complete outer periphery to said sheets in the area of said seam, whereby the seam areas between said sheets are bonded to each other and to said member in an unbroken bond and the wall of said tubelike member will take the principal strain ol the steam in that area when said object is inflated and subjected to internal air pressure; and a separate semi-rigid tube member inserted in the opening provided by said tube-like member.

2. A compartmented inflatable article, including in combination two facing sheets sealed together around their edges to define an enclosed inflatable space between vthem and sealed together along rat least one seam in between said edges to divide said space into a plurality of adjacent compartments communicating with each other, the lcommunication comprising an envelope extending across each said seam and to which said sheets are bonded, whereby al1 'said compartments are walled in by side seams Aadaptedtowit'hstand the loads imposed by inflation and any weight resting on it; and a semi-rigid tube inserted in said envelope to hold it open throughout its length.

3. A compartmented inllatable article, including in combination two facing sheets bonded together around the edges to dene an enclosed inllatable space between them and having at least one bonded seam in between said edges to divide said space into a plurality of adjacent compartments communicating with each other, the communication comprising a self-supporting tube and a flexible envelope around said tube extending across said seam and bonded between said facing sheets along said seam.

4. A compartmented inflatable article, including in combination two facing sheets of thermoplastic material joined around the edges to define an enclosed inflatable space between them and bonded together along a plurality of seams in between said edges to divide said space into a multiplicity of compartments, adjacent compartments communicating with each other, via air passages across said seams, each air passage including a flexible tubular member interposed across said seam between said facing sheets and bonded to both said sheets, and a semi-rigid tube inserted in the opening provided by the said flexible tubular member.

5. A method of manufacturing a compartment wall for an inllatable article of the type comprising two facing sheets sealed together and having a plurality of comv municating compartments, said method comprising the steps of inserting a flattened tube so that its axis lies generally perpendicularly across where the compartment wall is to be formedk at the place where air transfer is desired; inserting inside said flattened tube a strip of material not bondable to said tube; fusing said sheets together and to the outer surface of said flattened tube, said strip preventing said tube walls from bonding to each other; withdrawing said strip from said tube; and inserting therein a substantially round self-supporting tube of semi-rigid material.

6. A method of manufacturing an air transfer passagev in a compartment wall made from two sheets of .thermoplastic material for an inflatable article of the type having communicating compartments, comprising the steps of inserting a double thickness'of a material that is bondable by heat to the wall; forming said wall by heat that fuses together the inner faces ofthe wall to each other and to the outer surface of said double thickness of material, by separating a portion of the latter to prevent them from sticking together; and inserting in the space between said double thickness a self-supporting tube.

7. A method of manufacturing a compartment wall for an inllatable article of the type made from two facing sheets of thermoplastic material and having communicating compartments, comprising the steps of inserting a doubled strip of thermoplastic material where air transfer is desired generally crosswise to the compartment wall Where it is to be formed; `separating a portion of the facing walls of said strip to prevent bonding during heating; heating said sheets to fuse together and to the outer surface of said strip to form said wall; and inserting between the opposite sides of said doubled strip a substantially round self-supporting tube of semi-rigid material.

8. A method of manufacturing a compartment wall for an intlatable article of thetype made from two facing sheets of thermoplastic material and having communicating compartments, comprising the steps of inserting a f the interior of said tube; and cementing therein a substantially round self-supporting tube of semi-rigid plastic material.

References Cited inthe le of this patent UNITED STATES PATENTS 5 802,526 Russell Oct. 24, 1905 1,198,687 Williams et al Sept. 19, 1916 FOREIGN PATENTS:

Austria June 25, 1935 Switzerland Aug. 1, 1931 Italy Dec. 27, 1935 Great Britain July 22, 1935 

